This invention relates to new ascorbic acid derivatives and to the control of nitrosamine formation in cooked, nitrite cured meats through use of these derivatives.
Cured meat products have been prepared for many years by treatment of fresh meat with an alkali metal nitrite-containing composition or with a composition containing a mixture of alkali metal nitrite and an alkali metal nitrate. The curing mixture generally contains other material including sodium chloride and sugar. Addition of spices to the mixture is optional. Ascorbic acid including isoascorbic acid (sometimes called erythorbic acid) or salts of ascorbic acid or isoascorbic acid are sometimes included to accelerate the formation of cured meat pigments.
The conventional alkali metal nitrite or nitrate-nitrite containing curing mixtures provide quite satisfactory cures insofar as cured-meat preservation, flavor, and development of the pink to red color characteristic of cured meats are concerned. Although nitrates have been used alone in curing mixtures, such mixtures must depend on bacterial action to convert the nitrates to nitrites during the curing process since, as yet, there is no practical substitute for the nitrite ion for curing meats.
Unfortunately, minute amounts of undesirable nitrosamines may occur in meats, particularly bacon, which have been cured with the conventional curing mixtures, and which have been cooked by methods in which the fats reach relatively high temperatures. For example, N-nitrosopyrrolidine and dimethylnitrosamine are found on frying bacon, the cook-out fat containing the largest proportion of these volatile nitrosamines with N-nitrosopyrrolidine being present in the greater amount. These nitrosamines are not found in the cured raw meats. Apparently, the temperature attained by the fats in frying or equivalent cooking processes, such as broiling, grilling, microwave heating, etc., facilitates the reaction of alkali metal nitrites and amines of the meat to form nitrosamines. Since N-nitrosopyrrolidine and dimethylnitrosamine have been found to be carcinogenic in tests on experimental animals, they are regarded as a potential hazard in human food products. It is desirable, therefore, to reduce, eliminate or prevent the formation of these substances in cooked meat products.
Ascorbic acid, erythorbic acid and certain salts and esters thereof have heretofore been investigated for their effect in inhibiting the formation of nitrosamines during the frying of bacon. For example, the results of an investigation upon the inhibitory effect of sodium ascorbate on N-nitrosodimethylamine in nitrite cured pork are reported in J. Sci. Food Argic., 1975, 26 (1), pp 47-53. A comparison of the effect of propyl gallate, piperazine, sodium ascorbate and ascorbyl palmitate on nitrosopyrrolidine formation in bacon is reported in J. Agric. Food Chem., 1976, 24 (2), pp 397-401. Other investigations have studied the effects of various esters of ascorbic acid on nitrosamine formation in pork. See, for example, J. Food Science 1976, 41 (1) pp 199-200. While many of the aforementioned compounds are effective in reducing to some extent the amount of nitrosamines formed in cooked, cured meat, all have their shortcomings. For example, sodium isoascorbate is not fully effective. Ascorbyl palmitate is more effective than sodium isoascorbate but we have found an inconsistent tendency for the activity of this compound to decrease with storage time. The sodium salt of ascorbyl palmitate is not useful. An ascorbic acid derivative which provides effective anti-nitrosamine activity over the storage life of the meat product in which it is incorporated is much to be desired.